It is important to locate and track objects to maintain appropriate inventory levels and to prevent stoppages in operations that require a supply of such objects.
For example, in drilling for oil, the drilling site must be constantly supplied with an adequate supply of tubular pipes which are to be inserted into a drilled hole on solid ground or under seawater from a drilling platform. To prevent drilling operations from being interrupted, it is desirable to carry out regular audits of pipes in order to know when supplies are running low. Since the pipes are heavy and usually made of steel, it is difficult to move them around for visual inspection of identifying markings or to count them when they are tightly stacked together. Moreover, it is not feasible to use normal RF ID tags for tracking because they do not communicate well in an environment of steel, mud, or water.